Candle Jakk's Mercenary Adventuring Company hosts a Warlord's School. Contrary to the name, which may very well change in the future, it is a school for learning and honing the finer points of 4e tactical combat, character optimization, and teamwork. The school idea grew out of the suggestion on OYT for running 4e games of Capture the Flag or other scrimmages to acclimate people to the combat mechanics and 4e's emphasis on tactics.
The Gauntlet arose from the adventure CORE1-6 in LFR. There is a room in the adventure with nigh on 20 minions. They all but fill the available space (at least until the DM figured out half of them were in another part of the room). CJMAC's Gauntlet is a 10x20 or 10x30 square room filled with minions. They occupy every square except for the opening 1 or 2 rows that serve as the characters' starting location. The goal is to arrive at the other end of the room.
The weak variant of the Gauntlet entails normal minion rules. The minions may or may not move to advance on the PCs as their fellows die.
The intermediate variant of the Gauntlet sees minions respawn on their initiative each turn. This allows the PCs to use area powers to open holes for the party to advance before the minions close in on them again. Unlike the weak variant, however, the minions do not fill in the holes with their standing number (thus opening holes elsewhere) but respawn within the vacant squares.
The hard variant of the Gauntlet entails minions respawning each turn. Each PC is responsible for opening his own path. Readied actions may or may not help; if the purpose of the exercise is to explore teamwork and coordinated actions through the ready action, then it should be a valid tactic; otherwise, the Gauntlet is testing individual ability with a secondary emphasis on teamwork and positioning (it is still better to end your turn adjacent to an ally because that is one less minion attacking you; you want to be able to reach a close burst 5 from the healer; etc).
Further variants are possible, such as mixing in actual monsters or trapped squares, but the Gauntlet itself is defined by a room entirely full of monsters (even though I now regret using that term for this particular type of scenario).